The present invention relates to an irrigation/aspiration apparatus for use such as in a cataractal operation for extracting the opaque lens of the eye.
As a method of cataractal operation, phacoemulsification is generally practiced widely in which the lens nucleus is crushed and emulsified by causing a crushing tip to effect ultrasonic vibrations, and the emulsified lens nucleus tissue is aspirated from an aspiration hole at a distal end of the tip. In such an operation, an irrigation fluid is supplied into the patient""s eye, and the drainage including the tissue particles and the residual cortex together with the supplied irrigation fluid is aspirated while maintaining the depth of the anterior chamber.
In recent years, a method called ultra-high vacuum phaco (UHVP) has come to be practiced in which vacuum pressure (aspiration pressure) is set to a high level for the purpose of the holding of the nucleus, the prevention of the rebound of the nucleus, the improvement of emulsification efficiency, and the like.
With such an operation, if the aspiration hole at the distal end of the tip is blocked by the lens nucleus and the like, and the vacuum pressure within an aspiration tube rises sharply, with the result that a phenomenon called a surge occurs. This is a phenomenon in which the supplied irrigation fluid in a quantity exceeding a set flow rate of aspiration (hereafter, referred to as aspiration rate) is transiently aspirated from the anterior chamber the moment the lens nucleus has been extracted. There are cases where, due to such a phenomenon, the replenishment of the irrigation fluid cannot catch up with the aspiration, making it impossible to maintain the depth of the anterior chamber. In particular, in UHVP in which the maximum vacuum pressure is set to a high level, the vacuum pressure within the aspiration tube is maintained at a higher level than usual, there is a tendency that the supplied irrigation fluid in a quantity exceeding the set aspiration rate is temporarily aspirated due to the surge, and the anterior chamber is likely to become crushed.
An object of the invention is to provide an irrigation/aspiration apparatus capable of maintaining the depth of the anterior chamber by the sufficient replenishment of the irrigation fluid with respect to the transient surge occurring when the blocked aspiration hole of the crushing tip is opened.
To overcome the above-described problems, the invention is characterized by having the following features.
(1) An irrigation/aspiration apparatus for ophthalmic surgery, comprising:
an irrigation fluid supplying unit, which supplies irrigation fluid into a patient eye;
an aspiration unit provided with a hand piece having an aspiration hole, which aspirates through the aspiration hole a removed tissue along with the irrigation fluid supplied into the patient eye;
a pressure sensor which detects vacuum pressure caused by the aspiration unit; and
a control unit connected to the irrigation fluid supplying unit and the pressure sensor, which varies at least one of irrigation rate and irrigation pressure by controlling the irrigation fluid supplying unit based on the detected vacuum pressure.
(2) The apparatus of (1), wherein the control unit controls the irrigation fluid supplying unit such that at least one of the irrigation rate and irrigation pressure is increased as the vacuum pressure is increased, and at least one of the irrigation rate and the irrigation pressure is decreased as the vacuum pressure is decreased.
(3) The apparatus of (1), wherein the control unit controls the irrigation fluid supplying unit such that at least one of the irrigation rate and the irrigation pressure is increased if a first predetermined vacuum pressure higher than a basic vacuum pressure is detected, and at least one of the irrigation rate and irrigation pressure is decreased if a second predetermined vacuum pressure lower than the first vacuum pressure, or the basic vacuum pressure is detected.
(4) The apparatus of (3), wherein the control unit controls the irrigation fluid supplying unit such that at least one of the irrigation rate and irrigation pressure is decreased when a predetermined time period is elapsed after the second vacuum pressure is detected.
(5) The apparatus of (3), further comprising:
a setting unit which sets at least one of the irrigation rate and irrigation pressure under the basic vacuum pressure, and which is connected to the control unit.
(6) The apparatus of (1), wherein:
the irrigation fluid supplying unit includes an irrigation bottle containing the irrigation fluid, a supporting member supporting the irrigation bottle, and a vertically moving mechanism which vertically moves the supporting member within a predetermined height range and which is connected to the control unit;
the control unit controls driving of the vertically moving mechanism based on the detected vacuum pressure.
(7) The apparatus of (1), wherein the aspiration unit includes an aspiration tube connected to the hand piece, and a pump which generates the vacuum pressure within the aspiration tube.
(8) The apparatus of (1), wherein:
the irrigation fluid supplying unit includes an irrigation tube, and a control valve which controls at least one of the irrigation rate and the irrigation pressure within the irrigation tube and which is connected to the control unit, and
the control unit controls the control valve based on the detected vacuum pressure.
The present disclosure relates to the subject matter contained in Japanese patent application No. 2000-27019 (filed on Feb. 4, 2000), which is expressly incorporated herein by reference in its entirety.